Study On Static And Dynamic Mechanical Properties Of Medium And Low Speed Magnetic Suspension Beam

With the rapid development of China’s economy,the transportation industry has achieved comprehensive and rapid development.Among them,the medium and low speed maglev has the characteristics of strong climbing ability,low noise,energy conservation and environmental protection,and has strong competitiveness in the field of medium and low volume rail transit.The track beam is an important part of the medium and low speed maglev infrastructure,bearing the role of train load and static load of bridge deck infrastructure in the entire maglev system.The research on the static and dynamic mechanical properties of the track beam from the perspective of monitoring is still less at home and abroad.Therefore,this paper relies on a medium and low speed maglev line to explore its static and dynamic mechanical properties through the combination of static load test and static and dynamic mechanical simulation of the track beam,aiming to provide theoretical guidance for intelligent monitoring of medium and low speed maglev lines.The main research work of this paper is as follows:(1)The static load crack resistance test of track beam is designed and implemented,and the application of FRP-OF self sensing sensor in track beam is systematically explored.Relying on a project,its single track 25 m standard box girder is taken as the research object.In the stage of track beam prefabrication,concrete strain gauge,temperature sensor,6measuring points quasi distributed 24 m FRP-OF self sensing sensor and other sensors are buried.The loading mode and the arrangement of strain and displacement sensors are designed with reference to the relevant specifications for static load test acceptance of track beams.The whole process static load test of the track beam from elastic deformation to cracking failure has been completed.During the test,the whole process data of each sensor measuring point was collected,and the failure form,crack cracking and development of the track beam were accurately recorded.The strain and deflection data of track beam before and after cracking are systematically analyzed,which has the same evolution law compared with similar projects.The response data of 24 m FRP-OF self sensing sensor in the process of the test was emphatically carried out and compared with the data of traditional strain gauge.The research shows that the FRP-OF self sensing sensor can better perceive the whole process of the track beam deformation,and its stability and durability are good.(2)The nonlinear finite element analysis model of static load crack resistance of track beam is established,and the basic parameters of damage analysis of track beam are obtained by comparing the model correction method with the test results.According to the finite element method and the finite element software ABAQUS,a nonlinear calculation model for the static load cracking test analysis of the track beam is established.The concrete plastic damage(CDP)model is used to simulate the cracking and failure process of the test beam in local areas.By comparing the load displacement,load strain and damage evolution with the final failure form,the basic parameters of the CDP model are constantly adjusted within a reasonable range and the approximate damage path of the track beam is selected,Provide basic parameters for subsequent dynamic analysis.At the same time,through simulation analysis,the research on the layout and location optimization of 24 m FRP OF self sensing sensors is more systematically and comprehensively explored,which can provide reference for related engineering applications.(3)The rigid flexible coupling model of medium and low speed maglev vehicle bridge is established,and the feasibility of dynamic monitoring application of FRP-OF self sensing sensor in actual operation is explored.The basic model of the track beam in the static simulation is introduced into the multibody dynamics software UM in the form of a flexible subsystem,and the vehicle bridge rigid flexible coupling model is established.The dynamic response of the track beam under the conditions of different vehicle speeds,vehicle weights,etc.is discussed,and the correctness of the model is proved by comparison with relevant documents.On this basis,the time history curve of the vertical reaction force of the rail beam maglev track fulcrum is obtained.With the help of ABAQUS,the dynamic analysis model of the rail beam under multi-point excitation is established.The concrete damage parameters and distribution form in the model are the parameters in the static model.The implicit dynamic analysis method is used to explore the characteristics of the dynamic deflection of the rail beam and the dynamic strain of the FRPOF self sensing sensor.Combined with relevant literature and engineering practice,The research shows that it is feasible to monitor the dynamic mechanical properties of track beams by using FRP-OF self sensing sensors in actual operation.